The pathogenicity of daily intakes of Cooperia oncophora larvae in growing calves

摘要: Abstract Groups of three 4 1 2 - month-old calves were offered a complete ruminant diet ad libitum and given, on 5 days each week for 20 weeks, either 0, 5000, 10 000 or Cooperia oncophora larvae. All killed weeks after recieving the last dose infection reduced liveweight gain by 13.5% but did not significantly affect voluntary dry matter intake produce any obvious clinical signs. No relationship was evident between rate larval worm burden faecal egg count. It appeared that degree acquired resistance developed in majority infected 8–10 weeks. At slaughter, early fourth stage larvae predominated four maximum recoveries from intestine only 1.5% total intake. The located duodenum anterior jejunum. Pathological changes restricted to areas surrounding worms consisted compression distortion villi contact with parasites. Slight hypoalbuminaemia occurred 7 13 post inoculation group which received larvae/day. There no significant effects serum protein, globulin, urea, calcium, magnesium phosphorus concentrations, skeletal composition.